Tapcons, PATS, Epoxy anchors, Red-Head expansion anchors, power spikes etc.) there were Rawl Plugs (made of fiber - then plastic later on) and lead shields. Some folks also like to lubricate anchors with oil or candle wax (much as you would do with wood thought - I’ve also heard that they work better with a oversized hole and a sliver of wood driven in.īefore there was any of this new-fangled stuff (e.g. Concrete with lots of hard embedded aggregate may also prove tricky.ĭrilling a slightly oversized hole might help - but possibly at the expense of anchor strength. Old well-cured concrete may be much harder than you might expect causing problems. You may also know that not all concrete is created equal. They also recommend that you blow the dust out of the hole - so maybe that’s one issue.Īs you also recognize it is often useful that the diameter clearance hole in the material to be fastened be a bit larger than the diameter of the fastener. They do recommend that the hole be 1/4 inch deeper than the fastener - so you seem OK there We also tried a similar product from Hilti - perhaps not as readily available - and maybe in larger diameters - that we had better luck with. I recall that may of my crews had comments similar to yours about their failings Tapcons are not my first choice for anchoring but they do have some fans. What did I do wrong? Should I have made larger holes in the steel plate? Should I have blown out the dust in the holes? The plate is fasted to the concrete though, because the screws self-tapped into both the concrete and the plate. They are all now standing proud and awkward. I tried a socket wrench and managed to twist the heads off three of the screws. Then I started driving the 1 1/4' screws.Īnd I couldn’t get a single one to seat fully! I stalled out a 1/2 corded drill, even when driving a screw, backing it out, then redriving. I used the prescribed Tapcon masonry bit of the right size (they say use 3/16' bit for 1/4' screws) and drilled to the prescribed depth (about 1 1/2'). I drilled 3/16' holes in the steel plate and concrete, using first an ordinary twist bit for the steel (maybe 1/8' thick) and then a masonry bit for the concrete.

So I sanded off most of the rust on that mounting plate, and started drilling holes. A Tapcon rep told me they would work fine, as long as I didn’t reuse the old anchor holes, but drilled new ones. I told the HOA I would fix it with those blue concrete screws (Tapcons). It didn’t move, though, because the rest of the rail was still tied down at about six places. On one side, the bolts rusted out, so there was nothing holding that rail down at the base of the stairs. They are bolted into the concrete at their bases. The building where I live has continuous steel guard rails running next to the front stairs and then around a wheelchair ramp.

Tapcon drill bit sizes chart